Devices having surface-mounted electrical components typically comprise a carrier, e.g., a printed circuit board, and one or more unhoused electrical components such as, for example, chips or electrical units which are disposed on the carrier and are electrically connected to the electrical conductors of the carrier. Wireless connections such as surface mounting, for example, are used to reduce the dimensions of the device. In the case of such SMD components (SMD=surface mounted device), bonding wires are not used to produce the electrical connection between contact areas of the electrical components and corresponding electrical conductor lands of the carrier. Instead, the electrical connection is produced between the electrical components and the carrier by way of a soldered connection using solder balls (often called “bumps”) between the contact area of the electrical components and the corresponding conductor land on the carrier.
Known devices that do not have bonding wires are “flip chips”, for example, in which the chip is mounted directly with the active contact side facing the carrier. Particularly small dimensions and short conductor lengths can therefore be attained by the use of electrically conductive bumps. In highly complex circuits, this technology is often the only reasonable way to produce connections, and can be used to create several thousand contacts, for instance, wherein the electrical connection is produced across all contacts simultaneously. Advantageously, the entire surface of the chip can be used for contacting. Various processes are used to produce a permanent electrical connection by way of the bumps, such as soldering, conductive bonding, pressure welding, and the like.
One problem associated with such devices is that of setting a defined distance between the surface-mounted electrical component and the carrier.
International Publication No. WO 2008/073432 makes known a remelt soldering process, in which a holding element with solder is used to press an electrical component onto a carrier. A filler of the no-flow underfill type, which contains spacers that enable a defined distance to be set between the electrical component and the carrier, is used for this purpose.
U.S. Publication No. 2007/0181992 makes known a method for connecting two chips, in the case of which solder balls (bumps) and a filler are applied onto the chip. Spacer elements are added to the filler to ensure that a required distance between the chips is set when the solder balls are reflowed to produce the electrical connection. The filler can be of the no-flow underfill type. For this purpose, the spacers are embedded in a fluid matrix which can be applied locally or over a large surface area.
U.S. Publication No. 2007/0235217 discloses a method, in the case of which polymer spacers are applied to the carrier surface and/or the surface of the electrical component, which ensure that the minimum distance is set when the surface-mounted electrical component and the carrier are connected. The electrical component with the solder balls thereof disposed on the contact areas is placed on the conductor lands of the carrier with positional accuracy, wherein the intermediate space can be filled with a filler, in particular, a no-flow underfill. The assembly is heated until the solder bumps are reflowed and a metallic connection is produced between the contact areas of the electrical component and the conductor lands of the carrier. A required distance is thereby set by way of the spacers.
Devices having very small solder bumps, e.g., with diameters of less than 100 μm, have the problem, however, that the electrical component can float on top of the filler or, if excessive contact force is applied during connecting, the distance between the electrical component and the carrier becomes too small since the filler is displaced laterally, thereby affecting the reliability of the structure or even enabling short circuits to occur between adjacent solder balls.
A problem addressed by the present invention is that of providing a method, by way of which the electrical component can be prevented from floating on top of the filler. Furthermore, a connection arrangement shall be provided, which has small solder balls in particular, and the reliability of which is improved.
The present inventive disclosure is directed toward overcoming one or more of the above-identified problems.